Printable View
I was watching the new North Face episodes called "Know Boundaries" they were talking about the 5 red flags. New snow, wind, temperature, recent activity, and whoomphing/cracking...
I guess it depends on risk tolerance. But when do you guys usually back down/not even go out at all. I'm sure it all depends on how much wind/snow, size of recent activity, ect.
Just trying to get a feel for it. Like 2 red flags and you'll stay away from any serious terrain.
i keep it pretty simple.
1) new snow/slab
2) a sliding surface
3) steep enough angle (over about 30 degrees)
4) a trigger (me)
take any one of those away and yer not directly in avy terrain.
i will back down IF i feel that the snow i'm poking at doesn't feel/sound quite right.
i NEVER don't go out at all. always options. the sketchier yer surroundings, the more you learn. just gotta know how to use the terrain wisely.
rog
Rog when you say a sliding surface do you mean something like an obvious ice crust, facets, something like that? Because it takes slab on top of weak snow, but isn't a bed surface usually stronger snow.
Just trying to get into your head
yes, something like that.Quote:
Originally Posted by BLOWhERPOW
a slab on top of a tilted ice rink works too. a bed surface can be many things. i am kinda intrigued by slabs that "bridge" over weak snow. very tricky sometimes. will it hold or will it not? good to be solo (less weight) and light on yer skis when crossing and making turns over the "bridge". nice when it works out.Quote:
Because it takes slab on top of weak snow, but isn't a bed surface usually stronger snow.
trust me, you don't want to go there:)Quote:
Just trying to get into your head
rog
Backcountry avalanche forecasting is concerned with minimising uncertainty about snowpack instability at a specific time and place. This makes it difficult to answer your question because you've only provided very general information. That said, you can prioritise your red flags in the following manner:
Class III. Weather factors. Mostly numeric data; there is high uncertainty about the relationship between weather data and avalanches.
*Warming, cooling, new snow, rain, etc.
*The snow may or may not be unstable.
Class II. Snowpack factors. Mostly rule-based data; medium uncertainty about the relationship between snowpack data and avalanches.
*Results of instability tests ( especially shear quality ), snow profiles, ski testing.
*Are there signs of instability? Is skier-triggering possible?
Class I. Instability factors. Mostly event-based; low uncertainty about the relationship between instability factors and avalanches.
*Cracking, whumpfing, avalanches.
*Skier-triggering is possible. Is there a significant chance of releasing an avalanche of Size 2 or greater?
If there is heavy accumulation of new snow, with wind, and warming, and whumpfs, then I'm going to be super careful because I know the snowpack is unstable. However, at that point I don't really care about the heavy accumulation, the wind, or the warming. I'm only concerned with the whumpfing, because it is a crystal clear sign of high snowpack instability. In this example, I've given the observation that reveals information about instability the most weight.
In the absence of direct signs of instability, I'd give the most weight to whatever observations revealed the most information about instability. In the case of weather, I would assign higher priority to recent wind/warming than to new snow amounts ( since new snow always has plenty of instabilities ), and in the case of snowpack factors, I would assign higher priority to shear quality / fracture character than to the # of taps in a compression test. Mostly because I know that the number of taps only provides indirect information about instability, whereas shear quality/fracture character reveals fairly direct information about instability. ( I hate to say it, but I honestly don't use snowpack tests or profiles all that much because I'm really only looking for specific things when I dig: what is the layering, what are the crystal forms, and does hardness increase uniformly with depth. I resort to snowpack tests when I find an instability and I'm curious about shear quality and fracture character. I'm providing this information here as an example of how I prioritise observations and red flags; you shouldn't do things this way unless you understand snow metamorphism from the cloud-to-the-ground. )
Anyway, this leads to the next concept: the dynamic, ongoing nature of backcountry avalanche forecasting is one thing that recreational backcountry skiers often don't understand very well. You continually revise your forecast as you integrate new observations, and a single piece of data that reveals information about instability has the power to completely change the forecast from "potential instability" to "high instability". New plans are in order if that's the case.
Regardless of any of my prattling, make conservative decisions when your uncertainty is high for any reason. High uncertainty is a sign that you lack the information to make sound judgments about risk. Finally, desire and uncertainty are an especially dangerous combination when unmanaged.